Abstract

The urban infrastructure serves as lifelines for the normal operation and sustainable development of the city. The heating pipeline is one of the most important infrastructures of the urban lifeline system. At present, the design of directly buried heating pipeline is mainly based on the stress failure criterion. Since the large diameter directly buried heating water pipeline is subjected to high temperature and high pressure loads, the initial state of the pipeline is in an elsato-plastic state, which makes the equivalent stress yielding criterion cannot be applied in this case. However, the existing elastic-plastic buckling analysis mainly focuses on the displacement or mechanical loading conditions, there is no reliable evaluation index to represent the true limit state of the heated pipeline. In this investigation, geometric configuration scanning tests were carried out for pipes with diameter equals 1020 mm. The actual nonstraightness and ovality of pipeline were statistically analyzed. Based on the true geometric model, nonlinear finite element models for thermal buckling analysis of buried large-diameter heating pipelines were established. The yielding, buckling and failure behaviors of this kind of thin walled shell structures under temperature loads in engineering practice were analyzed. Parametric analysis was finally performed to investigate trends of pipe stress, strain and deformation with the pipe loading and pipe geometric parameters. The derived results can provide guidance for the design and safety assessment of directly buried heating pipeline.

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